[The importance of electromagnetic articulography in studying tongue motor function in the framework of an orthodontic diagnosis].

Objective data are required for assessing the influence of movements of the tongue on the position of the teeth. Electromagnetic articulography (EMA) makes it possible to track movements of the tongue using the principle of inductive distance measurement. A helmet made of light but robust acrylic material serves as a carrier for three transmitter coils; these latter are located in front of the forehead, in front of the chin, and at the back of the neck. Receiver coils are fixed to the tip of the tongue and at various points on the dorsum of the tongue. The distance between the receiver coils and the transmitter coils is calculated in real time by means of a personal computer. The movement trajectories are displayed on the computer screen in different colors in X-Y coordinates. The movements of the tongue are recorded in patients with correctly positioned front teeth and compared with those in patients with a frontal open bite. The significance of electromagnetic articulography for dental research and functional treatment is demonstrated.